EEM Rewind: A metatarsal, a Jones, and a Lisfranc walk into a bar

Fifth metatarsal fractures are common, but not all lateral foot injuries are benign. Jones fractures carry a meaningful nonunion risk, and Lisfranc injuries are the classic missed medial midfoot injury after a twisting plantar-flexion mechanism.

Metatarsal fractures in the ED

• Base fifth metatarsal fractures: Tuberosity avulsion fractures are the most common fifth metatarsal injury and usually do well with a stiff shoe or walking boot plus weight bearing as tolerated.
• Jones fracture risk: A true proximal fifth metatarsal fracture occurs distal to the tuberosity and has a 10-15% nonunion risk because the blood supply is poor in that zone.
• Shaft and neck patterns: More distal fifth metatarsal shaft or neck fractures are often oblique and generally heal nonoperatively, though recovery commonly takes a couple of months.
• Central metatarsal stability: Isolated low-energy fractures of the second through fourth metatarsals are usually stable enough for a walking boot, while multiple or high-energy injuries deserve more protection.
• Stress fracture caveat: Second, third, and fourth metatarsal stress fractures can have a normal initial x-ray, so persistent focal pain after overuse still warrants immobilization and follow-up. We get into the practical splinting choices in the episode.

Lisfranc injuries and missed midfoot trauma

• Classic injury mechanism: Lisfranc injury follows a twisting force on a plantar-flexed, externally rotated foot, the setup seen after stepping in a hole or landing awkwardly.
• Medial midfoot red flag: Inability to bear weight with medial midfoot pain and tenderness after a twisting injury should be treated as Lisfranc until proven otherwise.
• Subtle radiographic clues: Plain films may look normal, but malalignment at the first or second tarsometatarsal joints and a tiny avulsion fleck sign are classic clues.
• Limits of advanced imaging: CT helps define bony injury for operative planning, but purely ligamentous Lisfranc injuries can still be missed, so the exam matters most. That nuance is worth hearing in the chapter.
• Initial ED disposition: Suspected or minimally displaced Lisfranc injuries need a posterior slab, non-weight bearing, and close orthopedic follow-up, while dislocation requires urgent reduction planning.

References:

1. Josefsson PO, et al. Closed treatment of Jones fracture. Good results in 40 cases after 11-26 years. Acta Orthop Scand. 1994;65(5):545-547. PMID: 7801760. 
2. O'Malley MJ, et al. Fractures of the distal shaft of the fifth metatarsal. "Dancer's fracture". Am J Sports Med. 1996;24(2):240-243. PMID: 8775129.
3.  St-Amant, M., Deng, F. Fleck sign (foot). Reference article, Radiopaedia.org. Link.
4. Grewal U, et al. Lisfranc injury: A review and simplified treatment algorithm. Foot (Edinb). 2020 Dec;45:101719.  Epub 2020 Jul 6. PMID: 33038662.